Recently, development of microfabrication technology has led to the downsizing of conventional chemical analytical systems, thus resulting in an increased attention being attracted toward the research on a microsystem produced by integrating on a substrate downsized analytical systems for mixing, reaction, separation, detection, and so on. In the microsystem, a fluorocarbon film is employed as a surface protective film of a flow channel because the fluorocarbon film has advantageous features such as excellent chemical resistance and a less adsorptive property for protein. To take the example of one of traditional Microsystems, one of fluorocarbon films such as CYTOP™ (made by Asahi Glass Co., Ltd.) is coated on a PDMS with inferior chemical resistance, thus realizing protection against an organic solvent and reduction in adsorption of fluorescent substance. Further, there is reported a technique in which a fluorocarbon film is patterned on a silicon substrate to fix protein on a specific position.
On the other hand, Japanese unexamined patent application publication No. 11-121438 (Patent document 1) discloses a plasma etching method characterized by a carbon/fluorine ratio of a CF polymer film being 1.1 to 1.8, said CF polymer being deposited on a resist film during an etching process. According to this method, a fluorocarbon film is formed on a substrate plane surface to be used as a protection film.
Patent document 1: Japanese unexamined patent application publication No. 11-121438.